Insulating material and method of making same



R. E. OTTMAN.

INSULATING NATERIAL AND METHOD OF MAKING SAME.

AFPLlCATiGIl HLED DEC. 10. I917.

LMSJEQ Patented June 6,1922.

lTE D STATES PATENT or-Fica.

ROBERT E. OTTMAN, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELEC-TRIO COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEWYORK.

INSULATING MATERIAL AND METHOD OF MAKING Specification of LettersPatent. Patentd June 6, 1922.

Application filed December 10, 1917. Serial No. 206,453.

To all whom it may concern Be it known that I, ROBERT E. OTT AN,

a citizen of the United States, residing at East Orange, in the countyof Essex, State of New Jersey, have invented certain new and usefulImprovements in Insulating Materia ls and Methods of Making Same, ofwhich the following. is a full, clear, concise, and exact description.

This invention relates particularly to a material for use between therows of dry cells in dry cell battery cabinets, but may also be availedof wherever similar insulating problems are presented.

In dry cell battery cabinets the cells are often so connected that adifi'erence of potential as high as 100 volts may exist between twocells in adjacent rows.- It is, therefore, desirable that adjacent rowsof cells be separated by some insulating material in addition to thepasteboard cartons containing individual cells. As a result of exposureto electrolyte leaking from clls whose zinc casings have becomeperforated after, long or heavy service, this insulating material, ifitabsorbs moisture or is chemically attacked by the constituents of theelectrolyte, loses its insulatin efficiency and permits shortcircuitswhic result in a heavy flow of. current and possibl in ignition of thecartons or separators. here is also a fire risk from cells which, onaccount oflong use, have a high internal resistance, since, if a shortcircuit develops either between cells or in the wiring, the resultingheavy flow of current may heat up the carbon in' these old cells to suchan extent as toignite either the cartons or the separators and eventhecells themselves.

It is, thereforefan object of my invention to provide an insulatingmaterial adapted for use between the celis of dry cell batteries, whichis substantially nonignitable and therefore. fire-proof and whichretains its insulatin perspective, an embodiment of my inven-' tioncomprising a sheet of electrically nonconducting fabric which may be.stiff paper. or thin flexible cardboard, and which has been impregnatedwith suitable ignition preventives. The process of impregnationpreferably consists of immersing sheets or strips of the paper,cardboard or other fabric in a solution containing the ignitionpreventives, a suitable solution comprising borax and ammonium phosphatein the proportions of one pound of borax (commercial grade) and threepounds of ammonium phosphate (com'.

mercial grade) to twenty-five pints of water. The paper or cardboard iskept in the solution until it is completely impregnated therewith, afterwhich it is throughly dried.

Each side of the dried fabric is coated with a moisture-proof paintwhich may suitably conslst of 40% (by weight) of linseed oil and (byweight) of a mixture of- Zinc; oxide 54% Calcium carbonate 45% Lampblack t 1% fabric and counteracts any contrary effectdue to the presenceof the fireproofing salts.

Each side of the fabric preferably receives a double coating of thiscompound.

The finished material is easily cut into desired shapes, and being toughand resilient, readily adapts itself to the spapes between battery cellsor the like. It does not absorb moisture nor is it chemically attackedby the constituents of d cell electrolytes; it can be ignited only witdifliculty, and if ignited does not continue to burn; and-it is anon-conductor of electricity. It is, therefore, particularly ada ted foruse as a separator between the cel s of dry cell batteries and forsimilar purposes.

What is claimed is: 1 1. The method of forming an electricallyinsulating 'material which consists in impregnating-a non-conductivefabric with a solution of borax and ammonium phosphate,

drying the impregnated fabric; and coating said fabric with amixture ofcalcium carbonate,'-zinc' oxide and linseed oil.

ioo

2. An electrical insulating material, cotning a coating comprisingcalcium carbonate, prising a sheet of fabric impregnated with zinc oxideand linseed Oll.

borax and ammonium phosphate, and having In witness whereof, I hereuntosubscribe 10 a waterproof coating. my name this 5th day of December A.D., 5 3. An electrical insulating material com- 1917.

prising a sheet of fabric impregnated with borax and ammonium phosphate,and hav- ROBERT E. OTTMAN.

